A conventional electric motor, such as disclosed in a Japanese invention patent application publication (Laid-open) No. 6-351185 (copy enclosed) as illustrated in FIG. 15 of this application, includes: an inner stator S secured on a base B, a plurality of tooth member sets T radially secured to an annular yoke Y having coil windings W wound on each tooth member set T and limited between two stopping fasteners Fr clamped on the tooth member set T, and an outer rotor R having magnets M secured thereon rotatably circumferentially disposed around the inner stator S having a shaft A coaxially secured to the outer rotor R.
However, such a conventional outer-rotor type electric motor has the following drawbacks:
1. Each tooth member set T includes plural tooth members clamped by an inner and an outer stopping fastener Fr for limiting the coil windings W as wound on the tooth members, thereby reducing the winding area and decreasing the coil windings on the stator and decreasing the torque output from such an electric motor. PA0 2. Each tooth member has only an inner lug T1 insertably fixed in the annular yoke Y, leaving the outer portion of the tooth member unstably suspending (without being supported) in the air to thereby easily cause vibrational shock or influence the magnetic fields between the stator and the rotor. PA0 3. Due to the unstable structure and assembly complexity when making the inner stator of such a conventional motor, it is merely suitable for making a "thin" or "flat" miniature motor, unable for producing a motor of higher torque output.
The present inventor has found the drawbacks of the conventional electric motor and invented the present motor having higher torque output and efficiency.